Question: Who is {subject} of {inventor or discoverer} of {Bogdanov-Takens bifurcation} ?
Paraphrase: Who is {subject} of {innovator or pioneer} of {Bogdanov-Takens bifurcation} ?
SPARQL (Wikidata): SELECT ?answer WHERE { wd:Q4937510 wdt:P61 ?X . ?X wdt:P101 ?answer}
Answer: differential geometry, bifurcation theory, theory of differential equations